1. Field of the Invention
The present invention relates to thermal conductivity materials and more particularly, to a magnesium alloy compound type thermal metal material formed by bonding a magnesium alloy and a thermal conductive gold, platinum, silver or copper alloy by means of stamping-forging or calendaring process, showing the best physical properties of magnesium and gold/platinum/silver/copper and having quick heat absorption and dissipation characteristics.
2. Description of the Related Art
The performance of a heat sink in an electronic product affects the service life of the electronic product. Conventional heat sinks are commonly extruded from aluminum. A heat sink extruded from aluminum does not provide satisfactory heat absorbing and dissipating effects. This old design of heat sink cannot meet the heat dissipation requirements of new generator electronic products. Nowadays, compound metal materials are developed for making heat sinks or the like. Taiwan Patent Publication Number 563846 discloses a compound type heat dissipation device, which comprises: a heat-transfer member, which comprises a thermal plate defining a thermal contact face for bridging a heat source, and a plurality of fins protruded from the thermal plate; and a heat dissipation member surrounding the fins of the heat transfer member to constitute a radiation fin having heat-transfer fins on the inside. The heat conduction of the heat-transfer member is better than the heat dissipation member. The heat dissipation efficiency of the heat dissipation member is superior to the heat-transfer member.
Regular commercial compound heat sinks may have different shapes, however they commonly use aluminum for the heat dissipation member and copper for the heat-transfer member for the reason that copper is an excellent heat conductive material, however the heat dissipation capability of copper is relatively lower than aluminum; aluminum has a relatively lower thermal conductivity but relatively higher heat dissipation capability. Therefore, aluminum and copper are intensively used together to make heat sinks. However, an aluminum copper compound type heat sink still cannot provide satisfactory heat dissipation and magnetic noise shielding effects.
Among light metals, magnesium alloy and aluminum alloy have the characteristics of high strength, high specific gravity, high rigidity, high impact resistant power, high wear resistant power, good reclaimability, and good magnetic noise shielding effect. Unlike aluminum alloy that has a long application history more than several centuries, magnesium is a new material widely studied for application in this latest decade. Most people in this industry are not familiar with the properties of magnesium. Further, it is complicated to use magnesium for making heat sinks. During processing of magnesium, magnesium may be burned out of caused to explode. Therefore, it is almost impossible to make heat sink from magnesium only. Because magnesium is a dangerous metal easy to react with oxygen, it may burn when melted and disposed in contact with oxygen. When burning magnesium is added with water, hydrogen will be produced to enhance the burning or even to cause explosion.
They are people trying to use magnesium alloy for making a heat sink. They commonly employ casting and semi-solid injection to shape the product. Because magnesium has a low flow index, it is difficult to make a thin sheet member from magnesium by casting, and the yield rate will be low. Fabrication of a heat sink from magnesium by casting may encounter the problems of thermal crack, oxidation, flown line, low strength, and deformation upon stripping from mold. Further, low tightness is another problem that affects heat dissipation performance.